A parts washer is an apparatus that cleans various parts including, but not limited to machinery and machine parts. Current parts washers generally use an aqueous cleaning solution to remove such things as grease, carbon, resins, tar, inks and other grime from dirty parts like engine parts, tools, etc. Parts washers have also been known to use hydrocarbon solvent cleaning solutions to clean parts.
A conventional automatic aqueous parts washer includes a housing with a door to access a cleaning chamber having tray disposed therein for supporting parts. A pump pulls a cleaning solution from a reservoir and delivers the cleaning solution under pressure to a series of nozzles directed toward the parts disposed on the tray. A heater disposed in the reservoir is also commonly used for increasing the temperature of the aqueous cleaning solution, when desirable.
A major disadvantage of conventional part washers is the inability of the heater to maintain the temperature of the aqueous cleaning solution in an effective range, i.e. 120° F. to 160° F. Aqueous cleaning solutions must be stabilized in the effective range during a cleaning cycle in order to properly clean parts. Conventional parts washers attempt to maintain the cleaning solution in the effective range by using a heater configured for the cleaning solution capacity and workload of the machine. Such conventional heating elements are usually immersion heaters in direct contact with the aqueous cleaning solution and when new, easily raise the temperature of the cleaning solution into the effective range. However, once parts washing has commenced, the cleaning solution temperature drops rapidly, usually in less than 5 minutes. The heating element at maximum rated output cannot maintain the temperature of the cleaning solution above 120° F., for any extended period of time which is required to clean parts effectively. The cleaning solution cools as a result of ambient losses to the surrounding environment, atomization of the cleaning solution as it exits the nozzles and heat energy dissipated into the parts to be cleaned to bring them up to solution temperature.
Another disadvantage, and basis for the above disadvantage, is that a significant majority of the conventional aqueous parts washers are sold and used in a commercial setting, such as a car dealership repair shop, or a residential setting. Standard 120 volt/single phase electrical circuits in commercial and residential settings are often limited to 15 amps. In rare instances a 20 amp circuit may be available. Usually, custom installation or retrofit of an 120 volt electrical circuit with power handling capability of more than 15 amps is necessary. This results in increased costs to the facility owner. Alternatively, 240 or 480 volts of single or multi-phase circuits may be installed, all at significant cost to the owner/operator. Moreover, parts washers designed to operate on increased capacity electrical circuits also cost more to manufacture. Accordingly, conventional parts washers cannot be modified to use additional heaters because the power capacity of the electrical circuits is limited.
Another disadvantage of prior art parts washers is that the immersion heater is in direct contact with the aqueous cleaning solution. During the parts washing process, sludge, scale and other particulates, which are common in aqueous cleaning solutions, accumulate and are baked on the heater elements resulting in buildup of scale deposits on the heater. The scale deposits then act as an insulator. As a result, over time, heat transfer to the cleaning solution becomes less efficient, energy/operating costs are increased, life expectancy of the heater elements is shorter and periodic maintenance is increased.
Therefore, there is a need in the art for an improved parts washing apparatus having a novel structure and function for adjusting, increasing and maintaining the temperature of an aqueous cleaning solution that is operational on a standard 120 volt/15 amp electrical circuit, requires substantially reduced maintenance and less operating energy, cleans longer and more batches of parts compared to conventional parts washers, and overcomes the aforementioned disadvantages of prior art parts washers.